Ambulatory ECG (A-ECG) monitoring has existed in one form or another since 1961. Although advances in technology have incorporated sophisticated computer processing of the A-ECG data, all major A-ECG analysis systems still require direct human interaction (an A-ECG Technician). Therefore, the clinical knowledge and competency of the technician is critical to the overall diagnostic accuracy and effectiveness of the A-ECG procedure. Guidelines and recommended standards for A-ECG technicians have been proposed over the past ten years. However, no professional clinical organization has produced or recommended a formal training program or school for A-ECG technicians. No formal, standardized method for quality assessment of A-ECG technician or A-ECG Laboratories exists today. The proposed research is to determine the feasibility of developing an A-ECG Training and Testing system within an interactive multimedia computer aided instruction environment. Instructional materials used within the core curriculum will include text, still and full motion video, graphics and animation, sound, and real A-ECG waveform data obtained from three clinically approved national A-ECG databases.